After a root which possesses a short a as its root-vowel in the original enunciation (the dhātupāṭha) and after which the Periphrastic Future tās is always devoid of the augment iṭ , thal the personal-ending of the liṭ (Perfect Tense), like tās does not get the augment iṭ ,
As Future पक्ता, Periphrastic पपक्थ, यष्टा, इयष्ट, शक्ता, शशक्थ ॥ Why do we say 'in the Original Enunciation'? Observe Future कर्ष्टा Periphrastic चकर्षिथ in which the अ of 'karsh' is the result of guna substitution. Why do we say 'having an अ'? Observe Future भेत्ता Periphrastic बिभेविथ, here the root-vowel is इ ॥ Why do we say \short अ\? Observe Future राद्धा Periphrastic रराधिथ from राध् the root-vowel being long आ ॥ The word तास्वत् is understood here also. Therefore we have जिघृक्षति, जिग्रहिथ ॥ Here the root ग्रह is anit before सन् 7.2.12 and not before तास् so it will not be anit before थ ॥ The words नित्यम् अनिटः are also understood here. Therefore the rule does not apply to आनञ्जिथ 7.4.71, 7.4.72. For the root अञ्जू (VII. 21) takes optionally इट् before तास् 7.2.44 as अञ्जिता and अङ्क्ता ॥,